Beating bar crushers, which are also called impact crushers, differ from hammer crushers in that beating bars are arranged, distributed over the circumference and connected rigidly to the respective rotor, on the rotors, which rotate about a horizontal axis, while individual hammers are arranged in a rotatingly movable manner on the circumference in hammer crushers. The beating bars usually extend—undivided or divided—over the entire length of the crushing space and have no gaps, which would be larger than tolerance or expansion joints, in the longitudinal direction of the rotor. In beating bar crushers, the material charged in first meets the beating bars rotating at a circumferential velocity of preferably 20-50 m/sec and is thrown by these onto impact mechanisms so as buffers or deflectors which are placed in opposed position on the respective rotor and is possibly thrown back and comminuted in the process. In hammer crushers the material is comminuted essentially by the mobile hammers.
Impact crushers have designs with one or two rotors.
An impact crusher with one rotor and two or more impact mechanisms, which form essentially the housing of the impact crusher and are pivotable about horizontal axes, is known from DE 197 03 583 A1. A similar impact crusher is known from DE 42 10 809 C2, where a process for changing the impact elements and/or impact bodies is proposed as well.
DE 21 07 919 C2 discloses a twin-rotor impact crusher with rotors, which rotate in the same direction in the direction in which the material is being conveyed and likewise operate against impact walls, and whose horizontal axes are in a plane inclined at an angle of 30° to the horizontal and of which the second rotor is arranged lower than the first one, and in which impact crusher the last of the impact walls associated with the first rotor is arranged such that the materials bouncing off therefrom reach the second rotor. Due to the rotors rotating in the same direction, the material slides obliquely downward between the rotors and the impact walls and only a few of the material reaches the wedge-shaped anvil arranged there. This twin-rotor impact crusher, which belongs to the state of the art, is relatively complicated due to the large number of mobile impact walls needed.
Finally, DE-OS 20 53 693 shows a rotor rotating device for an impact crusher with two rotors, which are arranged next to each other at the same level and rotate outwardly when viewed from the top, wherein impact plates arranged above the rotors are likewise necessary.